The present invention relates to devices, instruments and methods for performing percutaneous surgeries, particularly at locations deep within the body. One specific application of the invention concern devices, instruments and techniques for percutaneous, minimally invasive spinal surgery. In another aspect of the invention, the percutaneous surgery is performed under direct vision at any location in the body.
Traditional surgical procedures for pathologies located deep within the body can cause significant trauma to the intervening tissues. These open procedures often require a long incision, extensive muscle stripping, prolonged retraction of tissues, denervation and devascularization of tissue. Most of these surgeries require room time of several hours and several weeks of post-operative recovery time due to the use of general anesthesia and the destruction of tissue during the surgical procedure. In some cases, these invasive procedures lead to permanent scarring and pain that can be more severe than the pain leading to the surgical intervention.
Minimally invasive alternatives such as arthroscopic techniques reduce pain, post-operative recovery time and the destruction of healthy tissue. Orthopedic surgical patients have particularly benefited from minimally invasive surgical techniques. The site of pathology is accessed through portals rather than through a significant incision thus preserving the integrity of the intervening tissues. These minimally invasive techniques also often require only local anesthesia. The avoidance of general anesthesia reduces post-operative recovery time and the risk of complications.
Minimally invasive surgical techniques are particularly desirable for spinal and neurosurgical applications because of the need for access to locations deep within the body and the danger of damage to vital intervening tissues. For example, a common open procedure for disc herniation, laminectomy followed by discectomy requires stripping or dissection of the major muscles of the back to expose the spine. In a posterior approach, tissue including spinal nerves and blood vessels around the dural sac, ligaments and muscle must be retracted to clear a channel from the skin to the disc. These procedures normally take at least one-two hours to perform under general anesthesia and require post-operative recovery periods of at least several weeks. In addition to the long recovery time, the destruction of tissue is a major disadvantage of open spinal procedures. This aspect of open procedures is even more invasive when the discectomy is accompanied by fusion of the adjacent vertebrae. Many patients are reluctant to seek surgery as a solution to pain caused by herniated discs and other spinal conditions because of the severe pain sometimes associated with the muscle dissection.
In order to reduce the post-operative recovery time and pain associated with spinal and other procedures, micro-surgical techniques have been developed. For example, in microsurgical discectomies, the disc is accessed by cutting a channel from the surface of the patient""s back to the disc through a small incision. An operating microscope or loupe is used to visualize the surgical field. Small diameter micro-surgical instruments are passed through the small incision and between two laminae and into the disc. The intervening tissues are disrupted less because the incision is smaller. Although these micro-surgical procedures are less invasive, they still involve some of the same complications associated with open procedures, such as injury to the nerve root and dural sac, perineural scar formation, reherniation at the surgical site and instability due to excess bone removal.
Other attempts have been made for minimally invasive procedures to correct symptomatic spinal conditions. One example is chemonucleolysis which involved the injection of an enzyme into the disc to partially dissolve the nucleus to alleviate disc herniation. Unfortunately, the enzyme, chymopapain, has been plagued by concerns about both its effectiveness and complications such as severe spasms, post-operative pain and sensitivity reactions including anaphylactic shock.
The development of percutaneous spinal procedures has yielded a major improvement in reducing recovery time and post-operative pain because they require minimal, if any, muscle dissection and they can be performed under local anesthesia. For example, U.S. Pat. No. 4,545,374 to Jacobson discloses a percutaneous lumbar discectomy using a lateral approach, preferably under fluoroscopic X-ray. This procedure is limited because it does not provide direct visualization of the discectomy site.
Other procedures have been developed which include arthroscopic visualization of the spine and intervening structure. U.S. Pat. Nos. 4,573,448 and 5,395,317 to Kambin disclose percutaneous decompression of herniated discs with a posterolateral approach. Fragments of the herniated disc are evacuated through a cannula positioning against the annulus. The ""317 Kambin patent discloses a biportal procedure which involves percutaneously placing both a working cannula and a visualization cannula for an endoscope. This procedure allows simultaneous visualization and suction, irrigation and resection in disc procedures.
Unfortunately, disadvantages remain with these procedures and accompanying tools because they are limited to a specific application or approach. For example, Jacobson, Kambin, and other references require a lateral or a postero-lateral approach for percutaneous discectomy. These approaches seek to avoid damage to soft tissue structures and the need for bone removal because it was thought to be impractical to cut and remove bone through a channel. However, these approaches do not address other spinal conditions which may require a mid-line approach, removal of bone, or insertion of implants or other technique.
U.S. Pat. No. 5,439,464 to Shapiro discloses a method and instruments for performing arthroscopic spinal surgeries such as laminectomies and fusions with a mid-line or medial posterior approach using three cannulae. Each of the cannulae requires a separate incision. While Shapiro discloses an improvement over prior procedures which were limited to a posterolateral or lateral approach for disc work, Shapiro""s procedure still suffers from many of the disadvantages of known prior percutaneous spinal surgery techniques and tools. One disadvantage of the Shapiro procedure is its requirement of a fluid work space. Another significant detriment is that the procedure requires multiple portals into the patient.
Fluid is required in these prior procedures to maintain the working space for proper function of optics fixed within a prior art cannula and inserted percutaneously. Irrigation, or the introduction of fluid into the working space, can often be logistically disadvantageous and even dangerous to the patient for several reasons. The introduction of fluid into the working space makes hemostasis more difficult and may damage surrounding tissue. Excess fluid may dangerously dilute the sodium concentration of the patient""s blood supply which can cause seizures or worse. The fluid environment can also make drilling difficult due to cavitation. The requirement for a fluid environment generally increases expenses associated with the surgery and adds to the complexity of the surgery, due in part to the relatively high volume of fluid required.
A need has remained for devices and methods that provide for percutaneous minimally invasive surgery for all applications and approaches. A significant need is also present in this field for techniques and instruments that permit surgical procedures in the working space under direct vision while employing microscopic and endoscopic viewing systems. Procedures that reduce the number of entries into the patient are also highly desirable. The fields of spinal and neuro surgery particularly require devices and techniques that minimize the invasion into the patient and that are streamlined and concise in their application.
The present invention is directed to methods and devices for performing surgery in a patient. In one preferred form, the present invention contemplates a cannula that includes a working channel to provide access to a location in the patient along with the selective employment of an endoscopic viewing system or a microscopic viewing system to view the location through the working channel. In another preferred form, the present invention contemplates mounting of a clamp assembly on the proximal end of a cannula. The clamp assembly includes a viewing element mounting portion having a length along which a viewing element can be selectively positioned.
The present invention further contemplates an elongated cannula sized for introduction into a patient. The cannula defines a length and a working channel between a distal working end and an opposite proximal end. A clamp assembly having a viewing element mounting portion can be engaged to the cannula with the viewing element mounting portion extending proximally from the cannula. A viewing element can be selectively engaged at various positions along the length of the viewing element mounting portion.
In a further form, the present invention contemplates a device for supporting a viewing element during surgery in a patient. The device includes a cannula having a working channel defined by an inner surface that extends between a proximal end and a distal end of the cannula. A clamp assembly is engageable to the cannula by applying a clamping force to the inner surface and the outer surface of the cannula. The clamp assembly includes a viewing element mounting portion that extends proximally from the cannula. In one embodiment, the clamp assembly includes a foot that extends from the viewing element mounting portion. The foot has a channel positionable over the proximal end of the cannula. A lever arm is pivotably attached to the foot. The lever arm includes a cam member with a cam surface frictionally engageable to the outer surface of the cannula.
In yet another form, a device for performing surgery in a patient is provided that includes a cannula with a distal working end and a proximal end and a working channel extending therethrough. The cannula has a length between the proximal end and the distal end such that the proximal end is positioned at the skin level of the patient when said distal end is positioned at a desired location in the patient. A clamp assembly that supports a viewing element is engageable to the proximal end of the cannula. In a preferred form the viewing element includes an optics cannula that extends into the working channel.
According to another aspect of the invention, a kit for use in percutaneous surgery is provided. The kit includes an elongated cannula having a working channel extending between a distal working end and an opposite proximal end. The kit further includes a clamp assembly removably engageable to the cannula and a viewing element supportable by the clamp assembly with an optics cannula of the viewing element in the working channel. The kit also includes a microscope positionable over the proximal end of the cannula.
The present invention also contemplates surgical methods and techniques employing the instruments and devices described herein.
These and other aspects, forms, features, objects, and advantages are further described in the following description of the illustrated embodiments.